Search for Solar Axions by the CERN Axion Solar Telescope with He3 Buffer Gas: Closing the Hot Dark Matter Gap
physical review letters2014Vol. 112pp. 091302-
164
2014physicalsearch
Abstract
The CERN Axion Solar Telescope has finished its search for solar axions with $^{3}\mathrm{He}$ buffer gas, covering the search range $0.64\text{ }\text{ }\mathrm{eV}\ensuremath{\lesssim}{m}_{a}\ensuremath{\lesssim}1.17\text{ }\text{ }\mathrm{eV}$. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of ${g}_{a\ensuremath{\gamma}}\ensuremath{\lesssim}3.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ at 95% C.L., with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of ${g}_{a\ensuremath{\gamma}}$, for example by the currently discussed next generation helioscope International AXion Observatory.